Medium: krb5

Issue Overview:

Authentication bypass by improper validation of certificate EKU and SAN
An authentication bypass flaw was found in the way krb5’s certauth interface handled the validation of client certificates. A remote attacker able to communicate with the KDC could potentially use this flaw to impersonate arbitrary principals under rare and erroneous circumstances.(CVE-2017-7562)

Invalid S4U2Self or S4U2Proxy request causes assertion failure
A denial of service flaw was found in MIT Kerberos krb5kdc service. An authenticated attacker could use this flaw to cause krb5kdc to exit with an assertion failure by making an invalid S4U2Self or S4U2Proxy request.( CVE-2017-11368)

Affected Packages:

krb5

Note:

This advisory is applicable to Amazon Linux 2 (AL2) Core repository. Visit this FAQ section for the difference between AL2 Core and AL2 Extras advisories.

Issue Correction:
Run yum update krb5 to update your system.

New Packages:

src:  
    krb5-1.15.1-19.amzn2.0.1.src  
  
x86_64:  
    krb5-devel-1.15.1-19.amzn2.0.1.x86_64  
    krb5-libs-1.15.1-19.amzn2.0.1.x86_64  
    krb5-server-1.15.1-19.amzn2.0.1.x86_64  
    krb5-server-ldap-1.15.1-19.amzn2.0.1.x86_64  
    krb5-workstation-1.15.1-19.amzn2.0.1.x86_64  
    krb5-pkinit-1.15.1-19.amzn2.0.1.x86_64  
    libkadm5-1.15.1-19.amzn2.0.1.x86_64  
    krb5-debuginfo-1.15.1-19.amzn2.0.1.x86_64  

Additional References

Red Hat: CVE-2017-11368, CVE-2017-7562

Mitre: CVE-2017-11368, CVE-2017-7562